1. Field of the Invention
The present invention relates to a semiconductor device mounting structure. Specifically, the present invention relates to a mounting structure for a semiconductor device used for electric power applications which requires cooling.
2. Background Information
Japanese Laid-Open Patent Publication No. 2000-102260 discloses one example of a conventional semiconductor device mounting structure utilizing a bus bar unit. As used herein throughout the disclosure of the present invention, a bus bar refers to a wiring structure for exchanging current between a semiconductor device and an external or peripheral device such as an electrical circuit element. In such conventional semiconductor mounting structure as disclosed in the above reference, the bus bar unit is mounted on a power-purpose semiconductor device and serves as a medium for transmitting a main current between the semiconductor device and an external electrical device. More specifically, the semiconductor device is connected to the electrical circuit element (for example, an electrolytic capacitor) by a pair of first bus bars and a second bus bar. The first bus bars are arranged so as to sandwich the second bus bar. An insulating material is disposed between the first bus bars and the second bus bars to insulate the first and second bus bar from each other. Several separate bus bars are also connected to the semiconductor device. Moreover, several separate bus bars are connected between the electrical circuit element and farther external electrical devices other than the semiconductor device.
If, for example, the semiconductor device in the conventional semiconductor device mounting structure as mentioned above operates at a high temperature, heat will be transmitted from the semiconductor device to the electrical circuit element through the first and second bus bars disposed between the semiconductor device and the electrical circuit element. Since the electrical resistance is proportional to the thermal resistance in all metals, heat is transmitted readily through metals that have low electrical resistance values. Thus, since the bus bars are required to have a low electrical resistance, heat is transmitted readily through the bus bars. Although the temperatures of the semiconductors generally do not exceed 150° C., wide-gap semiconductors have recently been used for power applications. Therefore, the problem of heat being transmitted through the bus bars from the semiconductor device to peripheral electrical circuit elements that are not very resistant to high temperatures is becoming increasingly significant.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved semiconductor device mounting structure. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.